Problem: Evaluate the following expression when $a = 9$ and $b = 2$. $4$ $a$ $ + 4$ $b$ $ - 9$
Answer: Substitute $9$ for ${a}$ and $2$ for ${b}$ $ = 4{(9)} + 4{(2)} - 9 $ $ = 36 + 8 - 9 $ $ = 35$